// All functions that need access to the editor's state live inside
// the CodeShard function. Below that, at the bottom of the file,
// some utilities are defined.

// CodeShard is the only global var we claim
var CodeShard = (function() {
    // This is the function that produces an editor instance. It's
    // closure is used to store the editor state.
    function CodeShard(place, givenOptions) {
        // Determine effective options based on given values and defaults.
        var options = {}, defaults = CodeShard.defaults;
        for (var opt in defaults)
            if (defaults.hasOwnProperty(opt))
                options[opt] = (givenOptions && givenOptions.hasOwnProperty(opt) ? givenOptions : defaults)[opt];
        
        // The element in which the editor lives. Takes care of scrolling
        // (if enabled).

        var debugconsole = document.getElementById("debugconsole");

        var reporter = {};

        function makeReporter(reportername) {
            reporter[reportername] = document.createElement("div");
            reporter[reportername].style.float = "left";
            reporter[reportername].style.clear = "both";
            reporter[reportername].style.border = "1px solid #ddd";
            var reporter_label = document.createElement("span");
            reporter[reportername].appendChild(reporter_label);
            var reporter_field  = document.createElement("span");
            reporter[reportername].appendChild(reporter_field);
            reporter_label.innerHTML = reportername + ": ";
            debugconsole.appendChild(reporter[reportername]);
            function report(val) {
                reporter_field.innerHTML = val;
            } 
            return report;
        }

        spanw_r =  makeReporter('spanw');
        childw_r =  makeReporter('childw');
        childtext_r = makeReporter('childtext');
        posx_r =  makeReporter('posx');

        var wrapper = document.createElement("span");

        wrapper.style.display = "inline-block";
        wrapper.style.width = "200px";

        wrapper.className = "CodeShard";
        // Work around http://www.quirksmode.org/bugreports/archives/2006/09/Overflow_Hidden_not_hiding.html
        if (window.ActiveXObject && /MSIE [1-7][\b\.]/.test(navigator.userAgent))
            wrapper.style.position = "relative";
        // This mess creates the base DOM structure for the editor.
        wrapper.innerHTML =
            '<span class="dcode" style="position: relative; overflow: hidden;">' + // Set to the height of the text, causes scrolling
            '<span class="dmeasure" style="position: absolute; height: 0; width: 0; overflow: hidden;">'+
            '<pre class="dmeasure-inner"></pre></span>'+
            '<span class="dmover" style="position: relative;z-index:0;">' + // Moved around its parent to cover visible view
            '<span class="CodeShard-gutter"><span class="CodeShard-gutter-text"></span></span>' +
            '<span style="overflow: hidden; position: absolute; top: 40px; left: 0">' + // Wraps and hides input textarea
            '<input type="text" style="position: absolute; top: 100px; left: 100px; width: 100000px;" /></span>' +
            // Provides positioning relative to (visible) text origin
            '<span class="CodeShard-lines" style="overflow: hidden; white-space:pre;"><span style="position: relative;">' +
            '<span class="CodeShard-cursor">&#160;</span>' + // Absolutely positioned blinky cursor
            '<span class="CodeShard-inner-wrap" style="max-width: 200px;overflow:hidden; white-space:pre;""></span>'+  // This SPAN contains the actual code
            '</span></span></span></span>';
        if (place.appendChild) place.appendChild(wrapper); else place(wrapper);
        // I've never seen more elegant code in my life.
        var code = wrapper.firstChild, 
        measure = code.firstChild.firstChild,
        mover = code.firstChild.nextSibling,
        gutter = mover.firstChild, 
        gutterText = gutter.firstChild,
        inputSpan = gutter.nextSibling, 
        input = inputSpan.firstChild,
        lineSpace = inputSpan.nextSibling.firstChild, 
        cursor = lineSpace.firstChild, 
        lineSpan = cursor.nextSibling;
        if (options.tabindex != null) input.tabindex = options.tabindex;
        if (!options.gutter && !options.lineNumbers) gutter.style.display = "none";
        
        // Delayed object wrap timeouts, making sure only one is active. blinker holds an interval.
        var poll = new Delayed(), highlight = new Delayed(), blinker;
        
        // mode holds a mode API object. lines an array of Line objects
        // (see Line constructor), work an array of lines that should be
        // parsed, and history the undo history (instance of History
        // constructor).
        var mode, lines = [new Line("")], work, history = new History(), focused;
        loadMode();
        // The selection. These are always maintained to point at valid
        // positions. Inverted is used to remember that the user is
        // selecting bottom-to-top.
        var sel = {from: {line: 0, ch: 0}, to: {line: 0, ch: 0}, inverted: false};
        // Selection-related flags. shiftSelecting obviously tracks
        // whether the user is holding shift. reducedSelection is a hack
        // to get around the fact that we can't create inverted
        // selections. See below.
        var shiftSelecting, reducedSelection, lastDoubleClick;
        // Variables used by startOperation/endOperation to track what
        // happened during the operation.
        var updateInput, changes, textChanged, selectionChanged, leaveInputAlone;
        // Current visible range (may be bigger than the view window).
        var showingFrom = 0, showingTo = 0, lastHeight = 0, curKeyId = null;
        // editing will hold an object describing the things we put in the
        // textarea, to help figure out whether something changed.
        // bracketHighlighted is used to remember that a backet has been
        // marked.
        var editing, bracketHighlighted;
        // Tracks the maximum line length so that the horizontal scrollbar
        // can be kept static when scrolling.
        var maxLine = "";
        // shardWidth holds the target width of the displayed Shard input widget,
        // set from options.
        var shardWidth = 200;

        // Initialize the content. Somewhat hacky (delayed prepareInput)
        // to work around browser issues.
        operation(function(){setValue(options.value || ""); updateInput = false;})();
        setTimeout(prepareInput, 20);
        
        // Register our event handlers.
        connect(wrapper, "mousedown", operation(onMouseDown));
        // Gecko browsers fire contextmenu *after* opening the menu, at
        // which point we can't mess with it anymore. Context menu is
        // handled in onMouseDown for Gecko.
        if (!gecko) connect(wrapper, "contextmenu", operation(onContextMenu));
        connect(code, "dblclick", operation(onDblClick));
        connect(wrapper, "scroll", function() {updateDisplay([]); if (options.onScroll) options.onScroll(instance);});
        connect(window, "resize", function() {updateDisplay(true);});
        connect(input, "keyup", operation(onKeyUp));
        connect(input, "keydown", operation(onKeyDown));
        connect(input, "keypress", operation(onKeyPress));
        connect(input, "focus", onFocus);
        connect(input, "blur", onBlur);
        
        connect(wrapper, "dragenter", function(e){e.stop();});
        connect(wrapper, "dragover", function(e){e.stop();});
        connect(wrapper, "drop", operation(onDrop));
        connect(wrapper, "paste", function(){input.focus(); fastPoll();});
        connect(input, "paste", function(){fastPoll();});
        connect(input, "cut", function(){fastPoll();});
        
        if (document.activeElement == input) onFocus();
        else onBlur();
        
        function isLine(l) {return l >= 0 && l < lines.length;}
        // The instance object that we'll return. Mostly calls out to
        // local functions in the CodeShard function. Some do some extra
        // range checking and/or clipping. operation is used to wrap the
        // call so that changes it makes are tracked, and the display is
        // updated afterwards.
        var instance = {
            getValue: getValue,
            setValue: operation(setValue),
            getSelection: getSelection,
            replaceSelection: operation(replaceSelection),
            focus: function(){input.focus(); onFocus(); fastPoll();},
            setOption: function(option, value) {
                options[option] = value;
                if (option == "lineNumbers" || option == "gutter") gutterChanged();
                else if (option == "mode" || option == "indentUnit") loadMode();
            },
            getOption: function(option) {return options[option];},
            undo: operation(undo),
            redo: operation(redo),
            indentLine: operation(function(n) {if (isLine(n)) indentLine(n, "smart");}),
            historySize: function() {return {undo: history.done.length, redo: history.undone.length};},
            matchBrackets: operation(function(){matchBrackets(true);}),
            getTokenAt: function(pos) {
                pos = clipPos(pos);
                return lines[pos.line].getTokenAt(mode, getStateBefore(pos.line), pos.ch);
            },
            cursorCoords: function(start){
                if (start == null) start = sel.inverted;
                return pageCoords(start ? sel.from : sel.to);
            },
            charCoords: function(pos){return pageCoords(clipPos(pos));},
            coordsChar: function(coords) {
                var off = eltOffset(lineSpace);
                var line = clipLine(Math.min(lines.length - 1, showingFrom + Math.floor((coords.y - off.top) / lineHeight())));
                return clipPos({line: line, ch: charFromX(clipLine(line), coords.x - off.left)});
            },
            getSearchCursor: function(query, pos, caseFold) {return new SearchCursor(query, pos, caseFold);},
            markText: operation(function(a, b, c){return operation(markText(a, b, c));}),
            setMarker: addGutterMarker,
            clearMarker: removeGutterMarker,
            setLineClass: operation(setLineClass),
            lineInfo: lineInfo,
            addWidget: function(pos, node, scroll) {
                var pos = localCoords(clipPos(pos), true);
                node.style.top = (showingFrom * lineHeight() + pos.yBot + paddingTop()) + "px";
                node.style.left = (pos.x + paddingLeft()) + "px";
                code.appendChild(node);
                if (scroll)
                    scrollIntoView(pos.x, pos.yBot, pos.x + node.offsetWidth, pos.yBot + node.offsetHeight);
            },
            
            lineCount: function() {return lines.length;},
            getCursor: function(start) {
                if (start == null) start = sel.inverted;
                return copyPos(start ? sel.from : sel.to);
            },
            somethingSelected: function() {return !posEq(sel.from, sel.to);},
            setCursor: operation(function(line, ch) {
                if (ch == null && typeof line.line == "number") setCursor(line.line, line.ch);
                else setCursor(line, ch);
            }),
            setSelection: operation(function(from, to) {setSelection(clipPos(from), clipPos(to || from));}),
            getLine: function(line) {if (isLine(line)) return lines[line].text;},
            setLine: operation(function(line, text) {
                if (isLine(line)) replaceRange(text, {line: line, ch: 0}, {line: line, ch: lines[line].text.length});
            }),
            removeLine: operation(function(line) {
                if (isLine(line)) replaceRange("", {line: line, ch: 0}, clipPos({line: line+1, ch: 0}));
            }),
            replaceRange: operation(replaceRange),
            getRange: function(from, to) {return getRange(clipPos(from), clipPos(to));},
            
            operation: function(f){return operation(f)();},
            refresh: function(){updateDisplay(true);},
            getInputField: function(){return input;},
            getWrapperElement: function(){return wrapper;}
        };
        
        function setValue(code) {
            history = null;
            var top = {line: 0, ch: 0};
            updateLines(top, {line: lines.length - 1, ch: lines[lines.length-1].text.length},
                        splitLines(code), top, top);
            history = new History();
        }
        function getValue(code) {
            var text = [];
            for (var i = 0, l = lines.length; i < l; ++i)
                text.push(lines[i].text);
            return text.join("\n");
        }
        
        function onMouseDown(e) {
            var ld = lastDoubleClick; lastDoubleClick = null;
            // First, see if this is a click in the gutter
            for (var n = e.target(); n != wrapper; n = n.parentNode)
                if (n.parentNode == gutterText) {
                    if (options.onGutterClick)
                        options.onGutterClick(instance, indexOf(gutterText.childNodes, n) + showingFrom);
                    return e.stop();
                }
            
            if (gecko && e.button() == 3) onContextMenu(e);
            if (e.button() != 1) return;
            // For button 1, if it was clicked inside the editor
            // (posFromMouse returning non-null), we have to adjust the
            // selection.
            var start = posFromMouse(e), last = start, going;
            if (!start) {if (e.target() == wrapper) e.stop(); return;}
            
            if (!focused) onFocus();
            e.stop();
            if (ld && +new Date - ld < 400) return selectLine(start.line);
            
            setCursor(start.line, start.ch, false);
            // And then we have to see if it's a drag event, in which case
            // the dragged-over text must be selected.
            function end() {
                input.focus();
                updateInput = true;
                move(); up();
            }
            function extend(e) {
                var cur = posFromMouse(e, true);
                if (cur && !posEq(cur, last)) {
                    if (!focused) onFocus();
                    last = cur;
                    setSelection(start, cur);
                    updateInput = false;
                    var visible = visibleLines();
                    if (cur.line >= visible.to || cur.line < visible.from)
                        going = setTimeout(operation(function(){extend(e);}), 150);
                }
            }
            
            var move = connect(document, "mousemove", operation(function(e) {
                clearTimeout(going);
                e.stop();
                extend(e);
            }), true);
            var up = connect(document, "mouseup", operation(function(e) {
                clearTimeout(going);
                var cur = posFromMouse(e);
                if (cur) setSelection(start, cur);
                e.stop();
                end();
            }), true);
        }
        function onDblClick(e) {
            var pos = posFromMouse(e);
            if (!pos) return;
            selectWordAt(pos);
            e.stop();
            lastDoubleClick = +new Date;
        }
        function onDrop(e) {
            var pos = posFromMouse(e, true), files = e.e.dataTransfer.files;
            if (!pos || options.readOnly) return;
            if (files && files.length && window.FileReader && window.File) {
                var n = files.length, text = Array(n), read = 0;
                for (var i = 0; i < n; ++i) loadFile(files[i], i);
                function loadFile(file, i) {
                    var reader = new FileReader;
                    reader.onload = function() {
                        text[i] = reader.result;
                        if (++read == n) replaceRange(text.join(""), clipPos(pos), clipPos(pos));
                    };
                    reader.readAsText(file);
                }
            }
            else {
                try {
                    var text = e.e.dataTransfer.getData("Text");
                    if (text) replaceRange(text, pos, pos);
                }
                catch(e){}
            }
        }
        function onKeyDown(e) {
            if (!focused) onFocus();
            
            var code = e.e.keyCode;
            // Tries to detect ctrl on non-mac, cmd on mac.
            var mod = (mac ? e.e.metaKey : e.e.ctrlKey) && !e.e.altKey, anyMod = e.e.ctrlKey || e.e.altKey || e.e.metaKey;
            if (code == 16 || e.e.shiftKey) shiftSelecting = shiftSelecting || (sel.inverted ? sel.to : sel.from);
            else shiftSelecting = null;
            // First give onKeyEvent option a chance to handle this.
            if (options.onKeyEvent && options.onKeyEvent(instance, addStop(e.e))) return;
            
            if (code == 33 || code == 34) {scrollPage(code == 34); return e.stop();} // page up/down
            if (mod && ((code == 36 || code == 35) || // ctrl-home/end
                        mac && (code == 38 || code == 40))) { // cmd-up/down
                scrollEnd(code == 36 || code == 38); return e.stop();
            }
            if (mod && code == 65) {selectAll(); return e.stop();} // ctrl-a
            if (!options.readOnly) {
                if (!anyMod && code == 13) {return;} // enter
                if (!anyMod && code == 9 && handleTab(e.e.shiftKey)) return e.stop(); // tab
                if (mod && code == 90) {undo(); return e.stop();} // ctrl-z
                if (mod && ((e.e.shiftKey && code == 90) || code == 89)) {redo(); return e.stop();} // ctrl-shift-z, ctrl-y
            }
            
            // Key id to use in the movementKeys map. We also pass it to
            // fastPoll in order to 'self learn'. We need this because
            // reducedSelection, the hack where we collapse the selection to
            // its start when it is inverted and a movement key is pressed
            // (and later restore it again), shouldn't be used for
            // non-movement keys.
            curKeyId = (mod ? "c" : "") + code;
            if (sel.inverted && movementKeys.hasOwnProperty(curKeyId)) {
                var range = selRange(input);
                if (range) {
                    reducedSelection = {anchor: range.start};
                    setSelRange(input, range.start, range.start);
                }
            }
            fastPoll(curKeyId);
        }
        function onKeyUp(e) {
            if (reducedSelection) {
                reducedSelection = null;
                updateInput = true;
            }
            if (e.e.keyCode == 16) shiftSelecting = null;
        }
        function onKeyPress(e) {
            if (options.onKeyEvent && options.onKeyEvent(instance, addStop(e.e))) return;
            if (options.electricChars && mode.electricChars) {
                var ch = String.fromCharCode(e.e.charCode == null ? e.e.keyCode : e.e.charCode);
                if (mode.electricChars.indexOf(ch) > -1)
                    setTimeout(operation(function() {indentLine(sel.to.line, "smart");}), 50);
            }
            var code = e.e.keyCode;
            // Re-stop tab and enter. Necessary on some browsers.
            if (code == 13) {handleEnter(); e.stop();}
            else if (code == 9 && options.tabMode != "default") e.stop();
            else fastPoll(curKeyId);
        }
        
        function onFocus() {
            if (!focused && options.onFocus) options.onFocus(instance);
            focused = true;
            slowPoll();
            if (wrapper.className.search(/\bCodeShard-focused\b/) == -1)
                wrapper.className += " CodeShard-focused";
            restartBlink();
        }
        function onBlur() {
            if (focused && options.onBlur) options.onBlur(instance);
            clearInterval(blinker);
            shiftSelecting = null;
            focused = false;
            wrapper.className = wrapper.className.replace(" CodeShard-focused", "");
        }
        
        // Replace the range from from to to by the strings in newText.
        // Afterwards, set the selection to selFrom, selTo.
        function updateLines(from, to, newText, selFrom, selTo) {
            if (history) {
                var old = [];
                for (var i = from.line, e = to.line + 1; i < e; ++i) old.push(lines[i].text);
                history.addChange(from.line, newText.length, old);
                while (history.done.length > options.undoDepth) history.done.shift();
            }
            updateLinesNoUndo(from, to, newText, selFrom, selTo);
        }
        function unredoHelper(from, to) {
            var change = from.pop();
            if (change) {
                var replaced = [], end = change.start + change.added;
                for (var i = change.start; i < end; ++i) replaced.push(lines[i].text);
                to.push({start: change.start, added: change.old.length, old: replaced});
                var pos = clipPos({line: change.start + change.old.length - 1,
                                   ch: editEnd(replaced[replaced.length-1], change.old[change.old.length-1])});
                updateLinesNoUndo({line: change.start, ch: 0}, {line: end - 1, ch: lines[end-1].text.length}, change.old, pos, pos);
            }
        }
        function undo() {unredoHelper(history.done, history.undone);}
        function redo() {unredoHelper(history.undone, history.done);}
        
        function updateLinesNoUndo(from, to, newText, selFrom, selTo) {
            var recomputeMaxLength = false, maxLineLength = maxLine.length;
            for (var i = from.line; i < to.line; ++i) {
                if (lines[i].text.length == maxLineLength) {recomputeMaxLength = true; break;}
            }
            
            var nlines = to.line - from.line, firstLine = lines[from.line], lastLine = lines[to.line];
            // First adjust the line structure, taking some care to leave highlighting intact.
            if (firstLine == lastLine) {
                if (newText.length == 1)
                    firstLine.replace(from.ch, to.ch, newText[0]);
                else {
                    lastLine = firstLine.split(to.ch, newText[newText.length-1]);
                    var spliceargs = [from.line + 1, nlines];
                    firstLine.replace(from.ch, firstLine.text.length, newText[0]);
                    for (var i = 1, e = newText.length - 1; i < e; ++i) spliceargs.push(new Line(newText[i]));
                    spliceargs.push(lastLine);
                    lines.splice.apply(lines, spliceargs);
                }
            }
            else if (newText.length == 1) {
                firstLine.replace(from.ch, firstLine.text.length, newText[0] + lastLine.text.slice(to.ch));
                lines.splice(from.line + 1, nlines);
            }
            else {
                var spliceargs = [from.line + 1, nlines - 1];
                firstLine.replace(from.ch, firstLine.text.length, newText[0]);
                lastLine.replace(0, to.ch, newText[newText.length-1]);
                for (var i = 1, e = newText.length - 1; i < e; ++i) spliceargs.push(new Line(newText[i]));
                lines.splice.apply(lines, spliceargs);
            }
            
            
            for (var i = from.line, e = i + newText.length; i < e; ++i) {
                var l = lines[i].text;
                if (l.length > maxLineLength) {
                    maxLine = l; maxLineLength = l.length;
                    recomputeMaxLength = false;
                }
            }
            if (recomputeMaxLength) {
                maxLineLength = 0;
                for (var i = 0, e = lines.length; i < e; ++i) {
                    var l = lines[i].text;
                    if (l.length > maxLineLength) {
                        maxLineLength = l.length; maxLine = l;
                    }
                }
            }
            
            // Add these lines to the work array, so that they will be
            // highlighted. Adjust work lines if lines were added/removed.
            var newWork = [], lendiff = newText.length - nlines - 1;
            for (var i = 0, l = work.length; i < l; ++i) {
                var task = work[i];
                if (task < from.line) newWork.push(task);
                else if (task > to.line) newWork.push(task + lendiff);
            }
            if (newText.length) newWork.push(from.line);
            work = newWork;
            startWorker(100);
            // Remember that these lines changed, for updating the display
            changes.push({from: from.line, to: to.line + 1, diff: lendiff});
            textChanged = {from: from, to: to, text: newText};
            
            // Update the selection
            function updateLine(n) {return n <= Math.min(to.line, to.line + lendiff) ? n : n + lendiff;}
            setSelection(selFrom, selTo, updateLine(sel.from.line), updateLine(sel.to.line));
            
            // Make sure the scroll-size span has the correct height.
            code.style.height = (lines.length * lineHeight() + 2 * paddingTop()) + "px";
        }
        
        function replaceRange(code, from, to) {
            from = clipPos(from);
            if (!to) to = from; else to = clipPos(to);
            code = splitLines(code);
            function adjustPos(pos) {
                if (posLess(pos, from)) return pos;
                if (!posLess(to, pos)) return end;
                var line = pos.line + code.length - (to.line - from.line) - 1;
                var ch = pos.ch;
                if (pos.line == to.line)
                    ch += code[code.length-1].length - (to.ch - (to.line == from.line ? from.ch : 0));
                return {line: line, ch: ch};
            }
            var end;
            replaceRange1(code, from, to, function(end1) {
                end = end1;
                return {from: adjustPos(sel.from), to: adjustPos(sel.to)};
            });
            return end;
        }
        function replaceSelection(code, collapse) {
            replaceRange1(splitLines(code), sel.from, sel.to, function(end) {
                if (collapse == "end") return {from: end, to: end};
                else if (collapse == "start") return {from: sel.from, to: sel.from};
                else return {from: sel.from, to: end};
            });
        }
        function replaceRange1(code, from, to, computeSel) {
            var endch = code.length == 1 ? code[0].length + from.ch : code[code.length-1].length;
            var newSel = computeSel({line: from.line + code.length - 1, ch: endch});
            updateLines(from, to, code, newSel.from, newSel.to);
        }
        
        function getRange(from, to) {
            var l1 = from.line, l2 = to.line;
            if (l1 == l2) return lines[l1].text.slice(from.ch, to.ch);
            var code = [lines[l1].text.slice(from.ch)];
            for (var i = l1 + 1; i < l2; ++i) code.push(lines[i].text);
            code.push(lines[l2].text.slice(0, to.ch));
            return code.join("\n");
        }
        function getSelection() {
            return getRange(sel.from, sel.to);
        }
        
        var pollingFast = false; // Ensures slowPoll doesn't cancel fastPoll
        function slowPoll() {
            if (pollingFast) return;
            poll.set(2000, function() {
                startOperation();
                readInput();
                if (focused) slowPoll();
                endOperation();
            });
        }
        function fastPoll(keyId) {
            var missed = false;
            pollingFast = true;
            function p() {
                startOperation();
                var changed = readInput();
                if (changed == "moved" && keyId) movementKeys[keyId] = true;
                if (!changed && !missed) {missed = true; poll.set(80, p);}
                else {pollingFast = false; slowPoll();}
                endOperation();
            }
            poll.set(20, p);
        }
        
        // Inspects the textarea, compares its state (content, selection)
        // to the data in the editing variable, and updates the editor
        // content or cursor if something changed.
        function readInput() {
            var changed = false, text = input.value, sr = selRange(input);
            if (!sr) return false;
            var changed = editing.text != text, rs = reducedSelection;
            var moved = changed || sr.start != editing.start || sr.end != (rs ? editing.start : editing.end);
            if (!moved && !rs) return false;
            if (changed) {
                shiftSelecting = reducedSelection = null;
                if (options.readOnly) {updateInput = true; return "changed";}
            }
            
            // Compute selection start and end based on start/end offsets in textarea
            function computeOffset(n, startLine) {
                var pos = 0;
                for (;;) {
                    var found = text.indexOf("\n", pos);
                    if (found == -1 || (text.charAt(found-1) == "\r" ? found - 1 : found) >= n)
                        return {line: startLine, ch: n - pos};
                    ++startLine;
                    pos = found + 1;
                }
            }
            var from = computeOffset(sr.start, editing.from),
            to = computeOffset(sr.end, editing.from);
            // Here we have to take the reducedSelection hack into account,
            // so that you can, for example, press shift-up at the start of
            // your selection and have the right thing happen.
            if (rs) {
                from = sr.start == rs.anchor ? to : from;
                to = shiftSelecting ? sel.to : sr.start == rs.anchor ? from : to;
                if (!posLess(from, to)) {
                    reducedSelection = null;
                    sel.inverted = false;
                    var tmp = from; from = to; to = tmp;
                }
            }
            
            // In some cases (cursor on same line as before), we don't have
            // to update the textarea content at all.
            if (from.line == to.line && from.line == sel.from.line && from.line == sel.to.line && !shiftSelecting)
                updateInput = false;
            
            // Magic mess to extract precise edited range from the changed
            // string.
            if (changed) {
                var start = 0, end = text.length, len = Math.min(end, editing.text.length);
                var c, line = editing.from, nl = -1;
                while (start < len && (c = text.charAt(start)) == editing.text.charAt(start)) {
                    ++start;
                    if (c == "\n") {line++; nl = start;}
                }
                var ch = nl > -1 ? start - nl : start, endline = editing.to - 1, edend = editing.text.length;
                for (;;) {
                    c = editing.text.charAt(edend);
                    if (c == "\n") endline--;
                    if (text.charAt(end) != c) {++end; ++edend; break;}
                    if (edend <= start || end <= start) break;
                    --end; --edend;
                }
                var nl = editing.text.lastIndexOf("\n", edend - 1), endch = nl == -1 ? edend : edend - nl - 1;
                updateLines({line: line, ch: ch}, {line: endline, ch: endch}, splitLines(text.slice(start, end)), from, to);
                if (line != endline || from.line != line) updateInput = true;
            }
            else setSelection(from, to);
            
            editing.text = text; editing.start = sr.start; editing.end = sr.end;
            return changed ? "changed" : moved ? "moved" : false;
        }
        
        // Set the textarea content and selection range to match the
        // editor state.
        function prepareInput() {
            var text = [];
            var from = Math.max(0, sel.from.line - 1), to = Math.min(lines.length, sel.to.line + 2);
            for (var i = from; i < to; ++i) text.push(lines[i].text);
            text = input.value = text.join(lineSep);
            var startch = sel.from.ch, endch = sel.to.ch;
            for (var i = from; i < sel.from.line; ++i)
                startch += lineSep.length + lines[i].text.length;
            for (var i = from; i < sel.to.line; ++i)
                endch += lineSep.length + lines[i].text.length;
            editing = {text: text, from: from, to: to, start: startch, end: endch};
            setSelRange(input, startch, reducedSelection ? startch : endch);
        }
        
        function scrollCursorIntoView() {
            var cursor = localCoords(sel.inverted ? sel.from : sel.to);
            return scrollIntoView(cursor.x, cursor.y, cursor.x, cursor.yBot);
        }
        function scrollIntoView(x1, y1, x2, y2) {
            var pl = paddingLeft(), pt = paddingTop();
            y1 += pt; y2 += pt; x1 += pl; x2 += pl;
            var screen = wrapper.clientHeight, screentop = wrapper.scrollTop, scrolled = false, result = true;
            if (y1 < screentop) {wrapper.scrollTop = Math.max(0, y1 - 10); scrolled = true;}
            else if (y2 > screentop + screen) {wrapper.scrollTop = y2 + 10 - screen; scrolled = true;}
            
            var screenw = wrapper.clientWidth, screenleft = wrapper.scrollLeft;
            if (x1 < screenleft) {wrapper.scrollLeft = Math.max(0, x1 - 10); scrolled = true;}
            else if (x2 > screenw + screenleft) {
                wrapper.scrollLeft = x2 + 10 - screenw;
                scrolled = true;
                if (x2 > code.clientWidth) result = false;
            }
            if (scrolled && options.onScroll) options.onScroll(instance);
            return result;
        }
        
        function visibleLines() {
            var lh = lineHeight(), top = wrapper.scrollTop - paddingTop();
            return {from: Math.min(lines.length, Math.max(0, Math.floor(top / lh))),
                    to: Math.min(lines.length, Math.ceil((top + wrapper.clientHeight) / lh))};
        }
        // Uses a set of changes plus the current scroll position to
        // determine which DOM updates have to be made, and makes the
        // updates.
        function updateDisplay(changes) {
            if (!wrapper.offsetWidth) {
                showingFrom = showingTo = 0;
                return;
            }
            // First create a range of theoretically intact lines, and punch
            // holes in that using the change info.
            var intact = changes === true ? [] : [{from: showingFrom, to: showingTo, domStart: 0}];
            for (var i = 0, l = changes.length || 0; i < l; ++i) {
                var change = changes[i], intact2 = [], diff = change.diff || 0;
                for (var j = 0, l2 = intact.length; j < l2; ++j) {
                    var range = intact[j];
                    if (change.to <= range.from)
                        intact2.push({from: range.from + diff, to: range.to + diff, domStart: range.domStart});
                    else if (range.to <= change.from)
                        intact2.push(range);
                    else {
                        if (change.from > range.from)
                            intact2.push({from: range.from, to: change.from, domStart: range.domStart})
                        if (change.to < range.to)
                            intact2.push({from: change.to + diff, to: range.to + diff,
                                          domStart: range.domStart + (change.to - range.from)});
                    }
                }
                intact = intact2;
            }
            
            // Then, determine which lines we'd want to see, and which
            // updates have to be made to get there.
            var visible = visibleLines();
            var from = Math.min(showingFrom, Math.max(visible.from - 3, 0)),
            to = Math.min(lines.length, Math.max(showingTo, visible.to + 3)),
            updates = [], domPos = 0, domEnd = showingTo - showingFrom, pos = from, changedLines = 0;
            
            for (var i = 0, l = intact.length; i < l; ++i) {
                var range = intact[i];
                if (range.to <= from) continue;
                if (range.from >= to) break;
                if (range.domStart > domPos || range.from > pos) {
                    updates.push({from: pos, to: range.from, domSize: range.domStart - domPos, domStart: domPos});
                    changedLines += range.from - pos;
                }
                pos = range.to;
                domPos = range.domStart + (range.to - range.from);
            }
            if (domPos != domEnd || pos != to) {
                changedLines += Math.abs(to - pos);
                updates.push({from: pos, to: to, domSize: domEnd - domPos, domStart: domPos});
            }
            
            if (!updates.length) return;
            lineSpan.style.display = "none";
            // If more than 30% of the screen needs update, just do a full
            // redraw (which is quicker than patching)
            if (changedLines > (visible.to - visible.from) * .3)
                refreshDisplay(from = Math.max(visible.from - 10, 0), to = Math.min(visible.to + 7, lines.length));
            // Otherwise, only update the stuff that needs updating.
            else

                patchDisplay(updates);
            lineSpan.style.display = "";
            
            // Position the mover span to align with the lines it's supposed
            // to be showing (which will cover the visible display)
            var different = from != showingFrom || to != showingTo || lastHeight != wrapper.clientHeight;
            showingFrom = from; showingTo = to;
            mover.style.top = (from * lineHeight()) + "px";
            if (different) {
                lastHeight = wrapper.clientHeight;
                code.style.height = (lines.length * lineHeight() + 2 * paddingTop()) + "px";
                updateGutter();
            }
            
            var textWidth = stringWidth(maxLine);
            //lineSpace.style.width = textWidth > wrapper.clientWidth ? textWidth + "px" : "";
            
            var childWidth = lineSpan.firstChild.offsetWidth;
            //var childWidth = measure.offsetWidth;
            childw_r(childWidth);
            childtext_r(lineSpan.firstChild.innerHTML);
            
            var spanw;
            if (shardWidth > childWidth)
                spanw = shardWidth - childWidth;
            else
                spanw = 0;

            spanw += "px";

            spanw_r(spanw);

            //lineSpan.style.marginRight = spanw;
            wrapper.style.position = "relative";
            
            //lineSpan.style.overflowX = "hidden";

            // Since this is all rather error prone, it is honoured with the
            // only assertion in the whole file.
            if (lineSpan.childNodes.length != showingTo - showingFrom)
                throw new Error("BAD PATCH! " + JSON.stringify(updates) + " size=" + (showingTo - showingFrom) +
                                " nodes=" + lineSpan.childNodes.length);

            updateCursor();
        }
        
        function refreshDisplay(from, to) {
            var html = [], start = {line: from, ch: 0}, inSel = posLess(sel.from, start) && !posLess(sel.to, start);
            for (var i = from; i < to; ++i) {
                var ch1 = null, ch2 = null;
                if (inSel) {
                    ch1 = 0;
                    if (sel.to.line == i) {inSel = false; ch2 = sel.to.ch;}
                }
                else if (sel.from.line == i) {
                    if (sel.to.line == i) {ch1 = sel.from.ch; ch2 = sel.to.ch;}
                    else {inSel = true; ch1 = sel.from.ch;}
                }
                html.push(lines[i].getHTML(ch1, ch2, true));
            }
            lineSpan.innerHTML = html.join("");
        }

        function patchDisplay(updates) {
            // Slightly different algorithm for IE (badInnerHTML), since
            // there .innerHTML on PRE nodes is dumb, and discards
            // whitespace.
            var sfrom = sel.from.line, sto = sel.to.line, off = 0,
            scratch = badInnerHTML && document.createElement("span");
            for (var i = 0, e = updates.length; i < e; ++i) {
                var rec = updates[i];
                var extra = (rec.to - rec.from) - rec.domSize;
                var nodeAfter = lineSpan.childNodes[rec.domStart + rec.domSize + off] || null;
                if (badInnerHTML)
                    for (var j = Math.max(-extra, rec.domSize); j > 0; --j)
                        lineSpan.removeChild(nodeAfter ? nodeAfter.previousSibling : lineSpan.lastChild);
                else if (extra) {
                    for (var j = Math.max(0, extra); j > 0; --j)
                        lineSpan.insertBefore(document.createElement("span"), nodeAfter);
                    for (var j = Math.max(0, -extra); j > 0; --j)
                        lineSpan.removeChild(nodeAfter ? nodeAfter.previousSibling : lineSpan.lastChild);
                }
                var node = lineSpan.childNodes[rec.domStart + off], inSel = sfrom < rec.from && sto >= rec.from;
                for (var j = rec.from; j < rec.to; ++j) {
                    var ch1 = null, ch2 = null;
                    if (inSel) {
                        ch1 = 0;
                        if (sto == j) {inSel = false; ch2 = sel.to.ch;}
                    }
                    else if (sfrom == j) {
                        if (sto == j) {ch1 = sel.from.ch; ch2 = sel.to.ch;}
                        else {inSel = true; ch1 = sel.from.ch;}
                    }
                    if (badInnerHTML) {
                        scratch.innerHTML = lines[j].getHTML(ch1, ch2, true);
                        lineSpan.insertBefore(scratch.firstChild, nodeAfter);
                    }
                    else {
                        node.innerHTML = lines[j].getHTML(ch1, ch2, false);
                        node.className = lines[j].className || "";
                        node = node.nextSibling;
                    }
                }
                off += extra;
            }
        }
        
        function updateGutter() {
            if (!options.gutter && !options.lineNumbers) return;
            var hText = mover.offsetHeight, hEditor = wrapper.clientHeight;
            gutter.style.height = (hText - hEditor < 2 ? hEditor : hText) + "px";
            var html = [];
            for (var i = showingFrom; i < showingTo; ++i) {
                var marker = lines[i].gutterMarker;
                var text = options.lineNumbers ? i + options.firstLineNumber : null;
                if (marker && marker.text)
                    text = marker.text.replace("%N%", text != null ? text : "");
                else if (text == null)
                    text = "\u00a0";
                html.push((marker && marker.style ? '<pre class="' + marker.style + '">' : "<pre>"), text, "</pre>");
            }
            gutter.style.display = "none";
            gutterText.innerHTML = html.join("");
            var minwidth = String(lines.length).length, firstNode = gutterText.firstChild, val = eltText(firstNode), pad = "";
            while (val.length + pad.length < minwidth) pad += "\u00a0";
            if (pad) firstNode.insertBefore(document.createTextNode(pad), firstNode.firstChild);
            gutter.style.display = "";
            lineSpace.style.marginLeft = gutter.offsetWidth + "px";
        }
        function updateCursor() {
            var head = sel.inverted ? sel.from : sel.to;
            var x = charX(head.line, head.ch) + "px";
            var y = (head.line - showingFrom) * lineHeight() + "px";
            inputSpan.style.top = y; inputSpan.style.left = x;
            if (posEq(sel.from, sel.to)) {
                cursor.style.top = y; cursor.style.left = x;
                cursor.style.display = "";
            }
            else cursor.style.display = "none";
        }
        
        // Update the selection. Last two args are only used by
        // updateLines, since they have to be expressed in the line
        // numbers before the update.
        function setSelection(from, to, oldFrom, oldTo) {
            if (posEq(sel.from, from) && posEq(sel.to, to)) return;
            var sh = shiftSelecting && clipPos(shiftSelecting);
            if (posLess(to, from)) {var tmp = to; to = from; from = tmp;}
            if (sh) {
                if (posLess(sh, from)) from = sh;
                else if (posLess(to, sh)) to = sh;
            }
            
            var startEq = posEq(sel.to, to), endEq = posEq(sel.from, from);
            if (posEq(from, to)) sel.inverted = false;
            else if (startEq && !endEq) sel.inverted = true;
            else if (endEq && !startEq) sel.inverted = false;
            
            // Some ugly logic used to only mark the lines that actually did
            // see a change in selection as changed, rather than the whole
            // selected range.
            if (oldFrom == null) {oldFrom = sel.from.line; oldTo = sel.to.line;}
            if (posEq(from, to)) {
                if (!posEq(sel.from, sel.to))
                    changes.push({from: oldFrom, to: oldTo + 1});
            }
            else if (posEq(sel.from, sel.to)) {
                changes.push({from: from.line, to: to.line + 1});
            }
            else {
                if (!posEq(from, sel.from)) {
                    if (from.line < oldFrom)
                        changes.push({from: from.line, to: Math.min(to.line, oldFrom) + 1});
                    else
                        changes.push({from: oldFrom, to: Math.min(oldTo, from.line) + 1});
                }
                if (!posEq(to, sel.to)) {
                    if (to.line < oldTo)
                        changes.push({from: Math.max(oldFrom, from.line), to: oldTo + 1});
                    else
                        changes.push({from: Math.max(from.line, oldTo), to: to.line + 1});
                }
            }
            sel.from = from; sel.to = to;
            selectionChanged = true;
        }
        function setCursor(line, ch) {
            var pos = clipPos({line: line, ch: ch || 0});
            setSelection(pos, pos);
        }
        
        function clipLine(n) {return Math.max(0, Math.min(n, lines.length-1));}
        function clipPos(pos) {
            if (pos.line < 0) return {line: 0, ch: 0};
            if (pos.line >= lines.length) return {line: lines.length-1, ch: lines[lines.length-1].text.length};
            var ch = pos.ch, linelen = lines[pos.line].text.length;
            if (ch == null || ch > linelen) return {line: pos.line, ch: linelen};
            else if (ch < 0) return {line: pos.line, ch: 0};
            else return pos;
        }
        
        function scrollPage(down) {
            var linesPerPage = Math.floor(wrapper.clientHeight / lineHeight()), head = sel.inverted ? sel.from : sel.to;
            setCursor(head.line + (Math.max(linesPerPage - 1, 1) * (down ? 1 : -1)), head.ch);
        }
        function scrollEnd(top) {
            setCursor(top ? 0 : lines.length - 1);
        }
        function selectAll() {
            var endLine = lines.length - 1;
            setSelection({line: 0, ch: 0}, {line: endLine, ch: lines[endLine].text.length});
        }
        function selectWordAt(pos) {
            var line = lines[pos.line].text;
            var start = pos.ch, end = pos.ch;
            while (start > 0 && /\w/.test(line.charAt(start - 1))) --start;
            while (end < line.length && /\w/.test(line.charAt(end))) ++end;
            setSelection({line: pos.line, ch: start}, {line: pos.line, ch: end});
        }
        function selectLine(line) {
            setSelection({line: line, ch: 0}, {line: line, ch: lines[line].text.length});
        }
        function handleEnter() {
            replaceSelection("\n", "end");
            if (options.enterMode != "flat")
                indentLine(sel.from.line, options.enterMode == "keep" ? "prev" : "smart");
        }
        function handleTab(shift) {
            shiftSelecting = null;
            switch (options.tabMode) {
            case "default":
                return false;
            case "indent":
                for (var i = sel.from.line, e = sel.to.line; i <= e; ++i) indentLine(i, "smart");
                break;
            case "classic":
                if (posEq(sel.from, sel.to)) {
                    if (shift) indentLine(sel.from.line, "smart");
                    else replaceSelection("\t", "end");
                    break;
                }
            case "shift":
                for (var i = sel.from.line, e = sel.to.line; i <= e; ++i) indentLine(i, shift ? "subtract" : "add");
                break;
            }
            return true;
        }
        
        function indentLine(n, how) {
            if (how == "smart") {
                if (!mode.indent) how = "prev";
                else var state = getStateBefore(n);
            }
            
            var line = lines[n], curSpace = line.indentation(), curSpaceString = line.text.match(/^\s*/)[0], indentation;
            if (how == "prev") {
                if (n) indentation = lines[n-1].indentation();
                else indentation = 0;
            }
            else if (how == "smart") indentation = mode.indent(state, line.text.slice(curSpaceString.length));
            else if (how == "add") indentation = curSpace + options.indentUnit;
            else if (how == "subtract") indentation = curSpace - options.indentUnit;
            indentation = Math.max(0, indentation);
            var diff = indentation - curSpace;
            
            if (!diff) {
                if (sel.from.line != n && sel.to.line != n) return;
                var indentString = curSpaceString;
            }
            else {
                var indentString = "", pos = 0;
                if (options.indentWithTabs)
                    for (var i = Math.floor(indentation / tabSize); i; --i) {pos += tabSize; indentString += "\t";}
                while (pos < indentation) {++pos; indentString += " ";}
            }
            
            replaceRange(indentString, {line: n, ch: 0}, {line: n, ch: curSpaceString.length});
        }
        
        function loadMode() {
            mode = CodeShard.getMode(options, options.mode);
            for (var i = 0, l = lines.length; i < l; ++i)
                lines[i].stateAfter = null;
            work = [0];
        }
        function gutterChanged() {
            var visible = options.gutter || options.lineNumbers;
            gutter.style.display = visible ? "" : "none";
            if (visible) updateGutter();
            else lineSpan.parentNode.style.marginLeft = 0;
        }
        
        function markText(from, to, className) {
            from = clipPos(from); to = clipPos(to);
            var accum = [];
            function add(line, from, to, className) {
                var line = lines[line], mark = line.addMark(from, to, className);
                mark.line = line;
                accum.push(mark);
            }
            if (from.line == to.line) add(from.line, from.ch, to.ch, className);
            else {
                add(from.line, from.ch, null, className);
                for (var i = from.line + 1, e = to.line; i < e; ++i)
                    add(i, 0, null, className);
                add(to.line, 0, to.ch, className);
            }
            changes.push({from: from.line, to: to.line + 1});
            return function() {
                var start, end;
                for (var i = 0; i < accum.length; ++i) {
                    var mark = accum[i], found = indexOf(lines, mark.line);
                    mark.line.removeMark(mark);
                    if (found > -1) {
                        if (start == null) start = found;
                        end = found;
                    }
                }
                if (start != null) changes.push({from: start, to: end + 1});
            };
        }
        
        function addGutterMarker(line, text, className) {
            if (typeof line == "number") line = lines[clipLine(line)];
            line.gutterMarker = {text: text, style: className};
            updateGutter();
            return line;
        }
        function removeGutterMarker(line) {
            if (typeof line == "number") line = lines[clipLine(line)];
            line.gutterMarker = null;
            updateGutter();
        }
        function setLineClass(line, className) {
            if (typeof line == "number") {
                var no = line;
                line = lines[clipLine(line)];
            }
            else {
                var no = indexOf(lines, line);
                if (no == -1) return null;
            }
            line.className = className;
            changes.push({from: no, to: no + 1});
            return line;
        }
        
        function lineInfo(line) {
            if (typeof line == "number") {
                var n = line;
                line = lines[line];
                if (!line) return null;
            }
            else {
                var n = indexOf(lines, line);
                if (n == -1) return null;
            }
            var marker = line.gutterMarker;
            return {line: n, text: line.text, markerText: marker && marker.text, markerClass: marker && marker.style};
        }
        
        function stringWidth(str) {
            measure.innerHTML = "<span><span>x</span></span>";
            measure.firstChild.firstChild.firstChild.nodeValue = str;
            return measure.firstChild.firstChild.offsetWidth || 10;
        }
        // These are used to go from pixel positions to character
        // positions, taking varying character widths into account.
        function charX(line, pos) {
            if (pos == 0) return 0;
            measure.innerHTML = "<pre><span>" + lines[line].getHTML(null, null, false, pos) + "</span></pre>";

            var childWidth = 0;

            childWidth += measure.firstChild.firstChild.offsetWidth;
            posx_r(childWidth);
            return childWidth;
        }
        function charFromX(line, x) {
            if (x <= 0) return 0;
            var lineObj = lines[line], text = lineObj.text;
            function getX(len) {
                measure.innerHTML = "<span><span>" + lineObj.getHTML(null, null, false, len) + "</span></span>";
                return measure.firstChild.firstChild.offsetWidth;
            }
            var from = 0, fromX = 0, to = text.length, toX;
            // Guess a suitable upper bound for our search.
            var estimated = Math.min(to, Math.ceil(x / stringWidth("x")));
            for (;;) {
                var estX = getX(estimated);
                if (estX <= x && estimated < to) estimated = Math.min(to, Math.ceil(estimated * 1.2));
                else {toX = estX; to = estimated; break;}
            }
            if (x > toX) return to;
            // Try to guess a suitable lower bound as well.
            estimated = Math.floor(to * 0.8); estX = getX(estimated);
            if (estX < x) {from = estimated; fromX = estX;}
            // Do a binary search between these bounds.
            for (;;) {
                if (to - from <= 1) return (toX - x > x - fromX) ? from : to;
                var middle = Math.ceil((from + to) / 2), middleX = getX(middle);
                if (middleX > x) {to = middle; toX = middleX;}
                else {from = middle; fromX = middleX;}
            }
        }
        
        function localCoords(pos, inLineWrap) {
            var lh = lineHeight(), line = pos.line - (inLineWrap ? showingFrom : 0);
            return {x: charX(pos.line, pos.ch), y: line * lh, yBot: (line + 1) * lh};
        }
        function pageCoords(pos) {
            var local = localCoords(pos, true), off = eltOffset(lineSpace);
            return {x: off.left + local.x, y: off.top + local.y, yBot: off.top + local.yBot};
        }
        
        function lineHeight() {
            var nlines = lineSpan.childNodes.length;
            if (nlines) return lineSpan.offsetHeight / nlines;
            measure.innerHTML = "<span>x</span>";
            return measure.firstChild.offsetHeight || 1;
        }
        function paddingTop() {return lineSpace.offsetTop;}
        function paddingLeft() {return lineSpace.offsetLeft;}
        
        function posFromMouse(e, liberal) {
            var off = eltOffset(lineSpace),
            x = e.pageX() - off.left,
            y = e.pageY() - off.top;
            // This is a mess of a heuristic to try and determine whether a
            // scroll-bar was clicked or not, and to return null if one was
            // (and !liberal).
            if (!liberal && e.target() != lineSpace.parentNode &&
                !(e.target() == wrapper && y > (lines.length * lineHeight()) && wrapper.clientHeight > code.offsetHeight))
                for (var n = e.target(); n != lineSpan && n != cursor; n = n.parentNode)
                    if (!n || n == wrapper) return null;
            var line = showingFrom + Math.floor(y / lineHeight());
            return clipPos({line: line, ch: charFromX(clipLine(line), x)});
        }
        function onContextMenu(e) {
            var pos = posFromMouse(e);
            if (!pos || window.opera) return; // Opera is difficult.
            if (posEq(sel.from, sel.to) || posLess(pos, sel.from) || !posLess(pos, sel.to))
                setCursor(pos.line, pos.ch);
            
            var oldCSS = input.style.cssText;
            input.style.cssText = "position: fixed; width: 30px; height: 30px; top: " + (e.pageY() - 1) +
                "px; left: " + (e.pageX() - 1) + "px; z-index: 1000; background: white; " +
                "border-width: 0; outline: none; overflow: hidden;";
            var val = input.value = getSelection();
            input.focus();
            setSelRange(input, 0, val.length);
            if (gecko) e.stop();
            leaveInputAlone = true;
            setTimeout(function() {
                if (input.value != val) operation(replaceSelection)(input.value, "end");
                input.style.cssText = oldCSS;
                leaveInputAlone = false;
                prepareInput();
                slowPoll();
            }, 50);
        }
        
        // Cursor-blinking
        function restartBlink() {
            clearInterval(blinker);
            var on = true;
            cursor.style.visibility = "";
            blinker = setInterval(function() {
                cursor.style.visibility = (on = !on) ? "" : "hidden";
            }, 650);
        }
        
        var matching = {"(": ")>", ")": "(<", "[": "]>", "]": "[<", "{": "}>", "}": "{<"};
        function matchBrackets(autoclear) {
            var head = sel.inverted ? sel.from : sel.to, line = lines[head.line], pos = head.ch - 1;
            var match = (pos >= 0 && matching[line.text.charAt(pos)]) || matching[line.text.charAt(++pos)];
            if (!match) return;
            var ch = match.charAt(0), forward = match.charAt(1) == ">", d = forward ? 1 : -1, st = line.styles;
            for (var off = pos + 1, i = 0, e = st.length; i < e; i+=2)
                if ((off -= st[i].length) <= 0) {var style = st[i+1]; break;}
            
            var stack = [line.text.charAt(pos)], re = /[(){}[\]]/;
            function scan(line, from, to) {
                if (!line.text) return;
                var st = line.styles, pos = forward ? 0 : line.text.length - 1, cur;
                for (var i = forward ? 0 : st.length - 2, e = forward ? st.length : -2; i != e; i += 2*d) {
                    var text = st[i];
                    if (st[i+1] != null && st[i+1] != style) {pos += d * text.length; continue;}
                    for (var j = forward ? 0 : text.length - 1, te = forward ? text.length : -1; j != te; j += d, pos+=d) {
                        if (pos >= from && pos < to && re.test(cur = text.charAt(j))) {
                            var match = matching[cur];
                            if (match.charAt(1) == ">" == forward) stack.push(cur);
                            else if (stack.pop() != match.charAt(0)) return {pos: pos, match: false};
                            else if (!stack.length) return {pos: pos, match: true};
                        }
                    }
                }
            }
            for (var i = head.line, e = forward ? Math.min(i + 50, lines.length) : Math.max(0, i - 50); i != e; i+=d) {
                var line = lines[i], first = i == head.line;
                var found = scan(line, first && forward ? pos + 1 : 0, first && !forward ? pos : line.text.length);
                if (found) {
                    var style = found.match ? "CodeShard-matchingbracket" : "CodeShard-nonmatchingbracket";
                    var one = markText({line: head.line, ch: pos}, {line: head.line, ch: pos+1}, style),
                    two = markText({line: i, ch: found.pos}, {line: i, ch: found.pos + 1}, style);
                    var clear = operation(function(){one(); two();});
                    if (autoclear) setTimeout(clear, 800);
                    else bracketHighlighted = clear;
                    break;
                }
            }
        }
        
        // Finds the line to start with when starting a parse. Tries to
        // find a line with a stateAfter, so that it can start with a
        // valid state. If that fails, it returns the line with the
        // smallest indentation, which tends to need the least context to
        // parse correctly.
        function findStartLine(n) {
            var minindent, minline;
            for (var search = n, lim = n - 40; search > lim; --search) {
                if (search == 0) return 0;
                var line = lines[search-1];
                if (line.stateAfter) return search;
                var indented = line.indentation();
                if (minline == null || minindent > indented) {
                    minline = search;
                    minindent = indented;
                }
            }
            return minline;
        }
        function getStateBefore(n) {
            var start = findStartLine(n), state = start && lines[start-1].stateAfter;
            if (!state) state = startState(mode);
            else state = copyState(mode, state);
            for (var i = start; i < n; ++i) {
                var line = lines[i];
                line.highlight(mode, state);
                line.stateAfter = copyState(mode, state);
            }
            if (!lines[n].stateAfter) work.push(n);
            return state;
        }
        function highlightWorker() {
            var end = +new Date + options.workTime;
            while (work.length) {
                if (!lines[showingFrom].stateAfter) var task = showingFrom;
                else var task = work.pop();
                if (task >= lines.length) continue;
                var start = findStartLine(task), state = start && lines[start-1].stateAfter;
                if (state) state = copyState(mode, state);
                else state = startState(mode);
                
                for (var i = start, l = lines.length; i < l; ++i) {
                    var line = lines[i], hadState = line.stateAfter;
                    if (+new Date > end) {
                        work.push(i);
                        startWorker(options.workDelay);
                        changes.push({from: task, to: i});
                        return;
                    }
                    var changed = line.highlight(mode, state);
                    line.stateAfter = copyState(mode, state);
                    if (hadState && !changed && line.text) break;
                }
                changes.push({from: task, to: i});
            }
        }
        function startWorker(time) {
            if (!work.length) return;
            highlight.set(time, operation(highlightWorker));
        }
        
        // Operations are used to wrap changes in such a way that each
        // change won't have to update the cursor and display (which would
        // be awkward, slow, and error-prone), but instead updates are
        // batched and then all combined and executed at once.
        function startOperation() {
            updateInput = null; changes = []; textChanged = selectionChanged = false;
        }
        function endOperation() {
            var reScroll = false;
            if (selectionChanged) reScroll = !scrollCursorIntoView();
            if (changes.length) updateDisplay(changes);
            else if (selectionChanged) updateCursor();
            if (reScroll) scrollCursorIntoView();
            if (selectionChanged) restartBlink();
            
            // updateInput can be set to a boolean value to force/prevent an
            // update.
            if (!leaveInputAlone && (updateInput === true || (updateInput !== false && selectionChanged)))
                prepareInput();
            
            if (selectionChanged && options.matchBrackets)
                setTimeout(operation(function() {
                    if (bracketHighlighted) {bracketHighlighted(); bracketHighlighted = null;}
                    matchBrackets(false);
                }), 20);
            var tc = textChanged; // textChanged can be reset by cursoractivity callback
            if (selectionChanged && options.onCursorActivity)
                options.onCursorActivity(instance);
            if (tc && options.onChange && instance)
                options.onChange(instance, tc);
        }
        var nestedOperation = 0;
        function operation(f) {
            return function() {
                if (!nestedOperation++) startOperation();
                try {var result = f.apply(this, arguments);}
                finally {if (!--nestedOperation) endOperation();}
                return result;
            };
        }
        
        function SearchCursor(query, pos, caseFold) {
            this.atOccurrence = false;
            if (caseFold == null) caseFold = typeof query == "string" && query == query.toLowerCase();
            
            if (pos && typeof pos == "object") pos = clipPos(pos);
            else pos = {line: 0, ch: 0};
            this.pos = {from: pos, to: pos};
            
            // The matches method is filled in based on the type of query.
            // It takes a position and a direction, and returns an object
            // describing the next occurrence of the query, or null if no
            // more matches were found.
            if (typeof query != "string") // Regexp match
                this.matches = function(reverse, pos) {
                    if (reverse) {
                        var line = lines[pos.line].text.slice(0, pos.ch), match = line.match(query), start = 0;
                        while (match) {
                            var ind = line.indexOf(match[0]);
                            start += ind;
                            line = line.slice(ind + 1);
                            var newmatch = line.match(query);
                            if (newmatch) match = newmatch;
                            else break;
                        }
                    }
                    else {
                        var line = lines[pos.line].text.slice(pos.ch), match = line.match(query),
                        start = match && pos.ch + line.indexOf(match[0]);
                    }
                    if (match)
                        return {from: {line: pos.line, ch: start},
                                to: {line: pos.line, ch: start + match[0].length},
                                match: match};
                };
            else { // String query
                if (caseFold) query = query.toLowerCase();
                var fold = caseFold ? function(str){return str.toLowerCase();} : function(str){return str;};
                var target = query.split("\n");
                // Different methods for single-line and multi-line queries
                if (target.length == 1)
                    this.matches = function(reverse, pos) {
                        var line = fold(lines[pos.line].text), len = query.length, match;
                        if (reverse ? (pos.ch >= len && (match = line.lastIndexOf(query, pos.ch - len)) != -1)
                            : (match = line.indexOf(query, pos.ch)) != -1)
                            return {from: {line: pos.line, ch: match},
                                    to: {line: pos.line, ch: match + len}};
                    };
                else
                    this.matches = function(reverse, pos) {
                        var ln = pos.line, idx = (reverse ? target.length - 1 : 0), match = target[idx], line = fold(lines[ln].text);
                        var offsetA = (reverse ? line.indexOf(match) + match.length : line.lastIndexOf(match));
                        if (reverse ? offsetA >= pos.ch || offsetA != match.length
                            : offsetA <= pos.ch || offsetA != line.length - match.length)
                            return;
                        for (;;) {
                            if (reverse ? !ln : ln == lines.length - 1) return;
                            line = fold(lines[ln += reverse ? -1 : 1].text);
                            match = target[reverse ? --idx : ++idx];
                            if (idx > 0 && idx < target.length - 1) {
                                if (line != match) return;
                                else continue;
                            }
                            var offsetB = (reverse ? line.lastIndexOf(match) : line.indexOf(match) + match.length);
                            if (reverse ? offsetB != line.length - match.length : offsetB != match.length)
                                return;
                            var start = {line: pos.line, ch: offsetA}, end = {line: ln, ch: offsetB};
                            return {from: reverse ? end : start, to: reverse ? start : end};
                        }
                    };
            }
        }
        
        SearchCursor.prototype = {
            findNext: function() {return this.find(false);},
            findPrevious: function() {return this.find(true);},
            
            find: function(reverse) {
                var self = this, pos = clipPos(reverse ? this.pos.from : this.pos.to);
                function savePosAndFail(line) {
                    var pos = {line: line, ch: 0};
                    self.pos = {from: pos, to: pos};
                    self.atOccurrence = false;
                    return false;
                }
                
                for (;;) {
                    if (this.pos = this.matches(reverse, pos)) {
                        this.atOccurrence = true;
                        return this.pos.match || true;
                    }
                    if (reverse) {
                        if (!pos.line) return savePosAndFail(0);
                        pos = {line: pos.line-1, ch: lines[pos.line-1].text.length};
                    }
                    else {
                        if (pos.line == lines.length - 1) return savePosAndFail(lines.length);
                        pos = {line: pos.line+1, ch: 0};
                    }
                }
            },
            
            from: function() {if (this.atOccurrence) return copyPos(this.pos.from);},
            to: function() {if (this.atOccurrence) return copyPos(this.pos.to);}
        };
        
        return instance;
    } // (end of function CodeShard)
    
    // The default configuration options.
    CodeShard.defaults = {
        value: "",
        mode: null,
        indentUnit: 2,
        indentWithTabs: false,
        tabMode: "classic",
        enterMode: "indent",
        electricChars: true,
        onKeyEvent: null,
        lineNumbers: false,
        gutter: false,
        shardWidth: 200,
        firstLineNumber: 1,
        readOnly: false,
        onChange: null,
        onCursorActivity: null,
        onGutterClick: null,
        onFocus: null, onBlur: null, onScroll: null,
        matchBrackets: false,
        workTime: 100,
        workDelay: 200,
        undoDepth: 40,
        tabindex: null
    };
    
    // Known modes, by name and by MIME
    var modes = {}, mimeModes = {};
    CodeShard.defineMode = function(name, mode) {
        if (!CodeShard.defaults.mode && name != "null") CodeShard.defaults.mode = name;
        modes[name] = mode;
    };
    CodeShard.defineMIME = function(mime, spec) {
        mimeModes[mime] = spec;
    };
    CodeShard.getMode = function(options, spec) {
        if (typeof spec == "string" && mimeModes.hasOwnProperty(spec))
            spec = mimeModes[spec];
        if (typeof spec == "string")
            var mname = spec, config = {};
        else
            var mname = spec.name, config = spec;
        var mfactory = modes[mname];
        if (!mfactory) {
            if (window.console) console.warn("No mode " + mname + " found, falling back to plain text.");
            return CodeShard.getMode(options, "text/plain");
        }
        return mfactory(options, config);
    }
    CodeShard.listModes = function() {
        var list = [];
        for (var m in modes)
            if (modes.propertyIsEnumerable(m)) list.push(m);
        return list;
    };
    CodeShard.listMIMEs = function() {
        var list = [];
        for (var m in mimeModes)
            if (mimeModes.propertyIsEnumerable(m)) list.push(m);
        return list;
    };
    
    CodeShard.fromInputField = function(textfield, options) {
        if (!options) options = {};
        options.value = textfield.value;
        if (!options.tabindex && textfield.tabindex)
            options.tabindex = textfield.tabindex;
        
        function save() {textfield.value = instance.getValue();}
        if (textfield.form) {
            // Deplorable hack to make the submit method do the right thing.
            var rmSubmit = connect(textfield.form, "submit", save, true);
            if (typeof textfield.form.submit == "function") {
                var realSubmit = textfield.form.submit;
                function wrappedSubmit() {
                    save();
                    textfield.form.submit = realSubmit;
                    textfield.form.submit();
                    textfield.form.submit = wrappedSubmit;
                }
                textfield.form.submit = wrappedSubmit;
            }
        }
        
        textfield.style.display = "none";
        var instance = CodeShard(function(node) {
            textfield.parentNode.insertBefore(node, textfield.nextSibling);
        }, options);
        instance.save = save;
        instance.toTextfield = function() {
            save();
            textfield.parentNode.removeChild(instance.getWrapperElement());
            textfield.style.display = "";
            if (textfield.form) {
                rmSubmit();
                if (typeof textfield.form.submit == "function")
                    textfield.form.submit = realSubmit;
            }
        };
        return instance;
    };
    
    // Utility functions for working with state. Exported because modes
    // sometimes need to do this.
    function copyState(mode, state) {
        if (state === true) return state;
        if (mode.copyState) return mode.copyState(state);
        var nstate = {};
        for (var n in state) {
            var val = state[n];
            if (val instanceof Array) val = val.concat([]);
            nstate[n] = val;
        }
        return nstate;
    }
    CodeShard.startState = startState;
    function startState(mode, a1, a2) {
        return mode.startState ? mode.startState(a1, a2) : true;
    }
    CodeShard.copyState = copyState;
    
    // The character stream used by a mode's parser.
    function StringStream(string) {
        this.pos = this.start = 0;
        this.string = string;
    }
    StringStream.prototype = {
        eol: function() {return this.pos >= this.string.length;},
        sol: function() {return this.pos == 0;},
        peek: function() {return this.string.charAt(this.pos);},
        next: function() {
            if (this.pos < this.string.length)
                return this.string.charAt(this.pos++);
        },
        eat: function(match) {
            var ch = this.string.charAt(this.pos);
            if (typeof match == "string") var ok = ch == match;
            else var ok = ch && (match.test ? match.test(ch) : match(ch));
            if (ok) {++this.pos; return ch;}
        },
        eatWhile: function(match) {
            var start = this.start;
            while (this.eat(match)){}
            return this.pos > start;
        },
        eatSpace: function() {
            var start = this.pos;
            while (/[\s\u00a0]/.test(this.string.charAt(this.pos))) ++this.pos;
            return this.pos > start;
        },
        skipToEnd: function() {this.pos = this.string.length;},
        skipTo: function(ch) {
            var found = this.string.indexOf(ch, this.pos);
            if (found > -1) {this.pos = found; return true;}
        },
        backUp: function(n) {this.pos -= n;},
        column: function() {return countColumn(this.string, this.start);},
        indentation: function() {return countColumn(this.string);},
        match: function(pattern, consume, caseInsensitive) {
            if (typeof pattern == "string") {
                function cased(str) {return caseInsensitive ? str.toLowerCase() : str;}
                if (cased(this.string).indexOf(cased(pattern), this.pos) == this.pos) {
                    if (consume !== false) this.pos += pattern.length;
                    return true;
                }
            }
            else {
                var match = this.string.slice(this.pos).match(pattern);
                if (match && consume !== false) this.pos += match[0].length;
                return match;
            }
        },
        current: function(){return this.string.slice(this.start, this.pos);}
    };
    
    // Line objects. These hold state related to a line, including
    // highlighting info (the styles array).
    function Line(text, styles) {
        this.styles = styles || [text, null];
        this.stateAfter = null;
        this.text = text;
        this.marked = this.gutterMarker = this.className = null;
    }
    Line.prototype = {
        // Replace a piece of a line, keeping the styles around it intact.
        replace: function(from, to, text) {
            var st = [], mk = this.marked;
            copyStyles(0, from, this.styles, st);
            if (text) st.push(text, null);
            copyStyles(to, this.text.length, this.styles, st);
            this.styles = st;
            this.text = this.text.slice(0, from) + text + this.text.slice(to);
            this.stateAfter = null;
            if (mk) {
                var diff = text.length - (to - from), end = this.text.length;
                function fix(n) {return n <= Math.min(to, to + diff) ? n : n + diff;}
                for (var i = 0; i < mk.length; ++i) {
                    var mark = mk[i], del = false;
                    if (mark.from >= end) del = true;
                    else {mark.from = fix(mark.from); if (mark.to != null) mark.to = fix(mark.to);}
                    if (del || mark.from >= mark.to) {mk.splice(i, 1); i--;}
                }
            }
        },
        // Split a line in two, again keeping styles intact.
        split: function(pos, textBefore) {
            var st = [textBefore, null];
            copyStyles(pos, this.text.length, this.styles, st);
            return new Line(textBefore + this.text.slice(pos), st);
        },
        addMark: function(from, to, style) {
            var mk = this.marked, mark = {from: from, to: to, style: style};
            if (this.marked == null) this.marked = [];
            this.marked.push(mark);
            this.marked.sort(function(a, b){return a.from - b.from;});
            return mark;
        },
        removeMark: function(mark) {
            var mk = this.marked;
            if (!mk) return;
            for (var i = 0; i < mk.length; ++i)
                if (mk[i] == mark) {mk.splice(i, 1); break;}
        },
        // Run the given mode's parser over a line, update the styles
        // array, which contains alternating fragments of text and CSS
        // classes.
        highlight: function(mode, state) {
            var stream = new StringStream(this.text), st = this.styles, pos = 0;
            var changed = false, curWord = st[0], prevWord;
            while (!stream.eol()) {
                var style = mode.token(stream, state);
                var substr = this.text.slice(stream.start, stream.pos);
                stream.start = stream.pos;
                if (pos && st[pos-1] == style)
                    st[pos-2] += substr;
                else if (substr) {
                    if (!changed && (st[pos+1] != style || (pos && st[pos-2] != prevWord))) changed = true;
                    st[pos++] = substr; st[pos++] = style;
                    prevWord = curWord; curWord = st[pos];
                }
                // Give up when line is ridiculously long
                if (stream.pos > 5000) {
                    st[pos++] = this.text.slice(stream.pos); st[pos++] = null;
                    break;
                }
            }
            if (st.length != pos) {st.length = pos; changed = true;}
            if (pos && st[pos-2] != prevWord) changed = true;
            return changed;
        },
        // Fetch the parser token for a given character. Useful for hacks
        // that want to inspect the mode state (say, for completion).
        getTokenAt: function(mode, state, ch) {
            var txt = this.text, stream = new StringStream(txt);
            while (stream.pos < ch && !stream.eol()) {
                stream.start = stream.pos;
                var style = mode.token(stream, state);
            }
            return {start: stream.start,
                    end: stream.pos,
                    string: stream.current(),
                    className: style || null,
                    state: state};
        },
        indentation: function() {return countColumn(this.text);},
        // Produces an HTML fragment for the line, taking selection,
        // marking, and highlighting into account.
        getHTML: function(sfrom, sto, includePre, endAt) {
            var html = [];
            if (includePre)
                html.push(this.className ? '<span class="' + this.className + '">': "<span>");
            function span(text, style) {
                if (!text) return;
                if (style) html.push('<span class="', style, '">', htmlEscape(text), "</span>");
                else html.push(htmlEscape(text));
            }
            var st = this.styles, allText = this.text, marked = this.marked;
            if (sfrom == sto) sfrom = null;
            var len = allText.length;
            if (endAt != null) len = Math.min(endAt, len);
            
            if (!allText && endAt == null)
                span(" ", sfrom != null && sto == null ? "CodeShard-selected" : null);
            else if (!marked && sfrom == null)
                for (var i = 0, ch = 0; ch < len; i+=2) {
                    var str = st[i], l = str.length;
                    if (ch + l > len) str = str.slice(0, len - ch);
                    ch += l;
                    span(str, st[i+1]);
                }
            else {
                var pos = 0, i = 0, text = "", style, sg = 0;
                var markpos = -1, mark = null;
                function nextMark() {
                    if (marked) {
                        markpos += 1;
                        mark = (markpos < marked.length) ? marked[markpos] : null;
                    }
                }
                nextMark();        
                while (pos < len) {
                    var upto = len;
                    var extraStyle = "";
                    if (sfrom != null) {
                        if (sfrom > pos) upto = sfrom;
                        else if (sto == null || sto > pos) {
                            extraStyle = " CodeShard-selected";
                            if (sto != null) upto = Math.min(upto, sto);
                        }
                    }
                    while (mark && mark.to != null && mark.to <= pos) nextMark();
                    if (mark) {
                        if (mark.from > pos) upto = Math.min(upto, mark.from);
                        else {
                            extraStyle += " " + mark.style;
                            if (mark.to != null) upto = Math.min(upto, mark.to);
                        }
                    }
                    for (;;) {
                        var end = pos + text.length;
                        var apliedStyle = style;
                        if (extraStyle) apliedStyle = style ? style + extraStyle : extraStyle;
                        span(end > upto ? text.slice(0, upto - pos) : text, apliedStyle);
                        if (end >= upto) {text = text.slice(upto - pos); pos = upto; break;}
                        pos = end;
                        text = st[i++]; style = st[i++];
                    }
                }
                if (sfrom != null && sto == null) span(" ", "CodeShard-selected");
            }
            if (includePre) html.push("</span>");
            return html.join("");
        }
    };
    // Utility used by replace and split above
    function copyStyles(from, to, source, dest) {
        for (var i = 0, pos = 0, state = 0; pos < to; i+=2) {
            var part = source[i], end = pos + part.length;
            if (state == 0) {
                if (end > from) dest.push(part.slice(from - pos, Math.min(part.length, to - pos)), source[i+1]);
                if (end >= from) state = 1;
            }
            else if (state == 1) {
                if (end > to) dest.push(part.slice(0, to - pos), source[i+1]);
                else dest.push(part, source[i+1]);
            }
            pos = end;
        }
    }
    
    // The history object 'chunks' changes that are made close together
    // and at almost the same time into bigger undoable units.
    function History() {
        this.time = 0;
        this.done = []; this.undone = [];
    }
    History.prototype = {
        addChange: function(start, added, old) {
            this.undone.length = 0;
            var time = +new Date, last = this.done[this.done.length - 1];
            if (time - this.time > 400 || !last ||
                last.start > start + added || last.start + last.added < start - last.added + last.old.length)
                this.done.push({start: start, added: added, old: old});
            else {
                var oldoff = 0;
                if (start < last.start) {
                    for (var i = last.start - start - 1; i >= 0; --i)
                        last.old.unshift(old[i]);
                    last.added += last.start - start;
                    last.start = start;
                }
                else if (last.start < start) {
                    oldoff = start - last.start;
                    added += oldoff;
                }
                for (var i = last.added - oldoff, e = old.length; i < e; ++i)
                    last.old.push(old[i]);
                if (last.added < added) last.added = added;
            }
            this.time = time;
        }
    };
    
    // Event stopping compatibility wrapper.
    function stopEvent() {
        if (this.preventDefault) {this.preventDefault(); this.stopPropagation();}
        else {this.returnValue = false; this.cancelBubble = true;}
    }
    // Ensure an event has a stop method.
    function addStop(event) {
        if (!event.stop) event.stop = stopEvent;
        return event;
    }
    
    // Event wrapper, exposing the few operations we need.
    function Event(orig) {this.e = orig;}
    Event.prototype = {
        stop: function() {stopEvent.call(this.e);},
        target: function() {return this.e.target || this.e.srcElement;},
        button: function() {
            if (this.e.which) return this.e.which;
            else if (this.e.button & 1) return 1;
            else if (this.e.button & 2) return 3;
            else if (this.e.button & 4) return 2;
        },
        pageX: function() {
            if (this.e.pageX != null) return this.e.pageX;
            else return this.e.clientX + document.body.scrollLeft + document.documentElement.scrollLeft;
        },
        pageY: function() {
            if (this.e.pageY != null) return this.e.pageY;
            else return this.e.clientY + document.body.scrollTop + document.documentElement.scrollTop;
        }
    };
    
    // Event handler registration. If disconnect is true, it'll return a
    // function that unregisters the handler.
    function connect(node, type, handler, disconnect) {
        function wrapHandler(event) {handler(new Event(event || window.event));}
        if (typeof node.addEventListener == "function") {
            node.addEventListener(type, wrapHandler, false);
            if (disconnect) return function() {node.removeEventListener(type, wrapHandler, false);};
        }
        else {
            node.attachEvent("on" + type, wrapHandler);
            if (disconnect) return function() {node.detachEvent("on" + type, wrapHandler);};
        }
    }
    
    function Delayed() {this.id = null;}
    Delayed.prototype = {set: function(ms, f) {clearTimeout(this.id); this.id = setTimeout(f, ms);}};
    
    // Some IE versions don't preserve whitespace when setting the
    // innerHTML of a PRE tag.
    var badInnerHTML = (function() {
        var pre = document.createElement("pre");
        pre.innerHTML = " "; return !pre.innerHTML;
    })();
    
    var gecko = /gecko\/\d{7}/i.test(navigator.userAgent);
    
    var lineSep = "\n";
    // Feature-detect whether newlines in textfields are converted to \r\n
    (function () {
        var te = document.createElement("textarea");
        te.value = "foo\nbar";
        if (te.value.indexOf("\r") > -1) lineSep = "\r\n";
    }());
    
    var tabSize = 8;
    var mac = /Mac/.test(navigator.platform);
    var movementKeys = {};
    for (var i = 35; i <= 40; ++i)
        movementKeys[i] = movementKeys["c" + i] = true;
    
    // Counts the column offset in a string, taking tabs into account.
    // Used mostly to find indentation.
    function countColumn(string, end) {
        if (end == null) {
            end = string.search(/[^\s\u00a0]/);
            if (end == -1) end = string.length;
        }
        for (var i = 0, n = 0; i < end; ++i) {
            if (string.charAt(i) == "\t") n += tabSize - (n % tabSize);
            else ++n;
        }
        return n;
    }
    
    // Find the position of an element by following the offsetParent chain.
    function eltOffset(node) {
        var x = 0, y = 0, n2 = node;
        for (var n = node; n; n = n.offsetParent) {x += n.offsetLeft; y += n.offsetTop;}
        for (var n = node; n != document.body; n = n.parentNode) {x -= n.scrollLeft; y -= n.scrollTop;}
        return {left: x, top: y};
    }
    // Get a node's text content.
    function eltText(node) {
        return node.textContent || node.innerText || node.nodeValue || "";
    }
    
    // Operations on {line, ch} objects.
    function posEq(a, b) {return a.line == b.line && a.ch == b.ch;}
    function posLess(a, b) {return a.line < b.line || (a.line == b.line && a.ch < b.ch);}
    function copyPos(x) {return {line: x.line, ch: x.ch};}
    
    function htmlEscape(str) {
        return str.replace(/[<&]/g, function(str) {return str == "&" ? "&amp;" : "&lt;";});
    }
    
    // Used to position the cursor after an undo/redo by finding the
    // last edited character.
    function editEnd(from, to) {
        if (!to) return from ? from.length : 0;
        if (!from) return to.length;
        for (var i = from.length, j = to.length; i >= 0 && j >= 0; --i, --j)
            if (from.charAt(i) != to.charAt(j)) break;
        return j + 1;
    }
    
    function indexOf(collection, elt) {
        if (collection.indexOf) return collection.indexOf(elt);
        for (var i = 0, e = collection.length; i < e; ++i)
            if (collection[i] == elt) return i;
        return -1;
    }
    
    // See if "".split is the broken IE version, if so, provide an
    // alternative way to split lines.
    if ("\n\nb".split(/\n/).length != 3)
        var splitLines = function(string) {
            var pos = 0, nl, result = [];
            while ((nl = string.indexOf("\n", pos)) > -1) {
                result.push(string.slice(pos, string.charAt(nl-1) == "\r" ? nl - 1 : nl));
                pos = nl + 1;
            }
            result.push(string.slice(pos));
            return result;
        };
    else
        var splitLines = function(string){return string.split(/\r?\n/);};
    
    // Sane model of finding and setting the selection in a textfield
    if (window.getSelection) {
        var selRange = function(te) {
            try {return {start: te.selectionStart, end: te.selectionEnd};}
            catch(e) {return null;}
        };
        var setSelRange = function(te, start, end) {
            try {te.setSelectionRange(start, end);}
            catch(e) {} // Fails on Firefox when textfield isn't part of the document
        };
    }
    // IE model. Don't ask.
    else {
        var selRange = function(te) {
            try {var range = document.selection.createRange();}
            catch(e) {return null;}
            if (!range || range.parentElement() != te) return null;
            var val = te.value, len = val.length, localRange = te.createTextRange();
            localRange.moveToBookmark(range.getBookmark());
            var endRange = te.createTextRange();
            endRange.collapse(false);
            
            if (localRange.compareEndPoints("StartToEnd", endRange) > -1)
                return {start: len, end: len};
            
            var start = -localRange.moveStart("character", -len);
            for (var i = val.indexOf("\r"); i > -1 && i < start; i = val.indexOf("\r", i+1), start++) {}
            
            if (localRange.compareEndPoints("EndToEnd", endRange) > -1)
                return {start: start, end: len};
            
            var end = -localRange.moveEnd("character", -len);
            for (var i = val.indexOf("\r"); i > -1 && i < end; i = val.indexOf("\r", i+1), end++) {}
            return {start: start, end: end};
        };
        var setSelRange = function(te, start, end) {
            var range = te.createTextRange();
            range.collapse(true);
            var endrange = range.duplicate();
            var newlines = 0, txt = te.value;
            for (var pos = txt.indexOf("\n"); pos > -1 && pos < start; pos = txt.indexOf("\n", pos + 1))
                ++newlines;
            range.move("character", start - newlines);
            for (; pos > -1 && pos < end; pos = txt.indexOf("\n", pos + 1))
                ++newlines;
            endrange.move("character", end - newlines);
            range.setEndPoint("EndToEnd", endrange);
            range.select();
        };
    }
    
    CodeShard.defineMode("null", function() {
        return {token: function(stream) {stream.skipToEnd();}};
    });
    CodeShard.defineMIME("text/plain", "null");
    
    return CodeShard;
})();
